What is clitellum? Give its function.

Explanation

### Step-by-Step Solution:

1. **Definition of Clitellum**: The clitellum is a glandular, thickened band-like structure found in certain annelids, particularly in earthworms.

2. **Location**: It is specifically found in the phylum Annelida and is characteristic of earthworms belonging to the class Oligochaeta.

3. **Function in Reproduction**: The clitellum serves a crucial role in reproduction. It is primarily associated with the female reproductive system in earthworms, especially in hermaphroditic species.

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